Known materials for use in electro-optic devices include both organic and inorganic materials. Semiconductor materials such as gallium arsenide, organic crystalline materials and organic materials prepared by sequential synthesis methods are used as well as electrically poled polymer films containing organic chromophores incorporated either physically to form composites or chemically to form homopolymer materials. See Kirk-Othmer Encyclopedia of Chemical Technology, 4th Edition, Volume 17 (John Wiley & Sons, New York, 1995) pp. 288–302.
When an electric field is applied to electro-optic materials, the highly polarizable electrons in those materials change significantly resulting in an increase in the index of refraction of the materials and a decrease in the speed of light passing through the materials. The change in the index of refraction can be used to impose electric signals onto optical signals to switch optical signals in a network or to control a beam of light.
The most commonly used inorganic material is lithium niobate which possesses an electro-optic coefficient on the of 35 pm/V which results in a typical drive voltage of about 5 volts. Because lithium niobate has a high dielectric constant which results in velocity mismatch of electric and optical waves propagating in the material, a short interaction length and limiting bandwidth results. In one analysis a one centimeter electro-optic modulator constructed from lithium niobate typically has a bandwidth of less the 10 Gigahertz.
In using organic materials systems, one obstacle to overcome is the decay of the poled electro-optic response at the elevated manufacturing and operating temperatures dictated by current electronic technology.
For generally useful devices, higher temperature electro-optic thermal stability is required. In some manufacturing processes, short-term temperature excursions can be high than 300 degrees C. In fabrication, the poling and curing temperatures of an electro-optic polymer for integrated devices may often exceed this limit.